This invention relates generally to metathesis chemistry. More particularly, it relates to organic metathesis chemistry.
Chemical reactions are generally performed in the liquid state, either in solution or in the melt. Liquid state chemistry is performed as a matter of expediency since the reactivity of end groups is enhanced in the liquid state as compared to the solid state.
Solid-state chemistry is known both in the single crystal as well as the semicrystalline solid-state array. For example, it has been demonstrated that single crystal to single crystal solid-state polymerization can occur in the case of diacetylene polymerization chemistry. In this case, no catalyst is present during the reaction but rather the reaction is initiated with light which converts monomer to polymer structures within the single crystal itself. Although a number of factors contribute to the occurrence of this chemistry, the principal factor is proximity. These are known as topological reactions and they exist in both small molecule as well as macromolecular chemistry. The reactions are relatively slow, yet the degree of order that exists in the molecules formed that have been studied is generally high.
Solid-state polymerization has also been demonstrated for systems which are catalyzed and results in condensation products. For example, polycondensation reactions which are conducted in the solid state can be combined with standard melt polymerization to produce well-known commercial molecules, such as polyester and nylon. However, reaction temperatures for these condensation reactions are typically 150xc2x0 C. or more. This process is often referred to as xe2x80x9cpost condensationxe2x80x9d and increases the average molecular weight of the molecules after the initial standard melt polymerization.
To date, solid state polycondensation reactions have been performed at high temperature because high temperature has been needed to facilitate the release of the small molecule that is produced, such as water, ethylene glycol, and the like from the solid state. The nature of the solid-state polymerization reaction is not fully understood though it is thought to be either the result of the diffusion of the small molecule out of a solid-state matrix or diffusion of a functional group from the center of the solid state matrix to its surface. Regardless of the mechanism, the reaction proceeds under relatively slow kinetics producing a high molecular weight structure.
Recently, metathesis chemistry has received much attention as a method to obtain precise structure control in polymer synthesis. Metathesis reactions involve an exchange, substitution, or replacement of atoms and radicals and are sometimes referred to as double dissociation reactions. Recent advances include the synthesis of polyolefin and polyolefin-like polymers through two-step procedures involving (1) acyclic diene metathesis (ADMET) polymerization or ring-opening metathesis polymerization (ROMP) followed by hydrogenation.
FIG. 1 shows some examples of metathesis reactions, such as acyclic diene metathesis (ADMET) and ring closing metathesis (RCM), ring opening metathesis (ROMP) and selective cross metathesis. As shown in FIG. 1, LnM=xe2x88x92R represents any metathesis catalyst (which are well known in the art) where Ln represents a ligand set, M represents a transition metal, and xe2x88x92R represents a hydrocarbon group. Further, R represents any functionality which does not deactivate the metathesis catalyst. All of these metathesis reactions can be useful for constructing molecules.
Currently, metathesis polymerization reactions and organic metathesis reactions forming small molecules require that a liquid state be achieved. In the case of metathesis polymerization reactions, the reaction proceeds via melt polymerization, often with the addition of other chemicals, such as solvents. It would be advantageous for metathesis to be performed at least in part in the solid state, allowing advantages associated with the use of low reaction temperatures (e.g. longer catalyst life) and solvent-less in-situ processing.
An in-situ method for performing organic metathesis polymer chemistry in the solid state includes the step of providing an organic monomer and a catalyst, the catalyst for driving a metathesis polymerization reaction of the monomer. The organic monomer can be provided as a liquid monomer. The reaction produces reaction products including a polymeric end product and at least one volatile reaction product. At least a portion of the volatile reaction product is removed during the reaction to favor formation of the reaction product. Significantly, the reaction is performed at a temperature being below an average melting point of the polymeric end product such that at least a portion of the reaction is performed in the solid phase. The reaction can comprise polycondensation metathesis chemistry (ADMET).
Volatile reaction product can be removed by passing an inert gas to carry away the volatile reaction product or applying a vacuum to remove the volatile reaction product.
The invention can be used with a variety of catalysts. For example, the catalyst can be a first generation Grubbs"" catalyst, a second generation Grubb""s catalyst, a Van der Schaaf catalyst or Schrock""s catalyst.
The reaction can be performed at a pressure of no more than approximately 1 atmosphere and at a temperature of no more than approximately 80xc2x0 C., preferably no more than approximately 50xc2x0 C., more preferably at a temperature of no more than approximately 30xc2x0 C. The reaction can be performed at a temperature above the glass transition temperature of the end product.
An in-situ method for forming cyclic molecules by metathesis chemistry in the solid state includes the steps of providing a non-ringed reagent and a catalyst, the catalyst for driving a ring closing metathesis reaction of the reagent, wherein the reaction produces a solid cyclic product and at least one volatile reaction product. At least a portion of the volatile reaction product is removed during the reaction to favor formation of the solid cyclic product. The reaction is performed at a temperature below a melting point of the cyclic product such that at least a portion of the reaction is performed in the solid phase. The reaction temperature can be no more than approximately 80xc2x0 C., preferably no more than approximately 50xc2x0 C., more preferably at a temperature of no more than approximately 30xc2x0 C.
An in-situ method for performing organic ring opening metathesis polymer (ROMP) chemistry in the solid state includes the steps of providing an organic ringed monomer and a catalyst, the catalyst for driving a metathesis polymerization reaction of the monomer, wherein the reaction opens the ringed monomer and forms a polymeric end product. The reaction is performed at a temperature below an average melting point of the polymeric end product such that at least a portion of the reaction is performed in the solid phase.
The reaction temperature can be no more than approximately 80xc2x0 C., preferably no more than approximately 50xc2x0 C., more preferably at a temperature of no more than approximately 30xc2x0 C.
A method for in-situ polymerization by metathesis chemistry in the solid state includes the steps of providing a monomer and a catalyst for driving a metathesis polymerization reaction of the monomer on a surface, the monomer forming an intractable polymer during solution polymerization, wherein the reaction produces reaction products including a polymeric end product and at least one volatile reaction product. At least a portion of the volatile reactant product is removed during the reaction to favor formation of the polymeric end product. The reaction can be performed at a temperature below an average melting point of the polymeric end product such that at least a portion of the reaction is performed in the solid phase.
The surface used for polymerization can comprises a mold and further comprising the step of casting the polymeric end product. The monomer can be phenylene vinylene.
The reaction temperature can be no more than approximately 80xc2x0 C., preferably no more than approximately 50xc2x0 C., more preferably at a temperature of no more than approximately 30xc2x0 C. The reaction can be performed at a temperature above the glass transition temperature of the polymeric end product.
A method for solid state metathesis polymerization includes the steps of providing an organic monomer having double or triple bonded end groups together with a metathesis catalyst having the formula LnM=xe2x88x92R, wherein Ln represents a ligand set, M represents a transition metal, and xe2x88x92R represents a hydrocarbon group, polymerizing the monomer, where the polymerization reaction produces a polymeric end product and at least one volatile reaction product. The reaction is performed at a temperature below an average melting point of the polymeric end product such that at least a portion of the polymerization is performed in the solid phase. The polymerization can be performed in-situ. The monomer can be a liquid monomer. The reaction temperature can be no more than approximately 80xc2x0 C., preferably no more than approximately 50xc2x0 C., more preferably at a temperature of no more than approximately 30xc2x0 C.